Figure 5.

Expression Levels of the DREB1A and DREB1B Genes in Response to Rapid and Slow Temperature Decreases.

(A) A schematic diagram of the temperatures around the plants during the rapid and slow temperature decreases. Three-week-old seedling of the wild-type and camta mutant plants grown in soil pots were immediately cooled from 22°C to 4°C (rapid) or were gradually cooled from 22°C to 4°C, with a decrease of 3°C every 10 min (slow). These cold treatments were started at ZT2.

(B) Expression levels of the DREB1 genes under the two different cold stress treatments. The transcript level of each gene in the plants treated for the indicated duration (0, 1, 2, 3, or 6 h) after the temperature began to decrease was measured by RT-qPCR. The values represent the average of three technical replicates, and the error bars indicate the sd. The maximum expression level of each gene in the wild-type plants exposed to a rapid temperature decrease was set to 100. The asterisks indicate significant differences (*P < 0.05 and **P < 0.01 according to Student’s t test) in the expression of each gene compared with that in the wild-type plants at each time point in three biological replicates using the plants sampled at different times.